Seven Segment LED Display

/ / Using a seven segment LED Display

At the junction, free electrons from the N-type material fill holes from the P-type material. This creates an insulating layer in the middle of the diode called the depletion zone.

When the negative end of the circuit is hooked up to the N-type layer and the positive end is hooked up to P-type layer, electrons and holes start moving and the depletion zone disappears.

A diode has two different semiconducting materials that allow electricity to flow in one direction only. One part is N-type material which has extra electrons. The other part is P-type material which has "holes" (particles that are missing electrons) into which electrons can move. What happens at the junction of the two materials is that the extra electrons from the N-type move to the "holes" in the P-type and create an area of no charge called the "depletion zone." The result is an area of N-type material, the depletion zone, and the P-type material.
When the N-type side is connected to the negative end of a battery and the P-type side to the positive end of the battery, the electrons in the N-type material are repelled and move across the P-type material. At the same time, the holes in the P-type material are repelled by the positive end. The result is a current. If you connect the ends of the battery in the opposite way, the current won't flow.
There are all sorts of LEDs. Some emit infrared light (your remote control) and others produce light of different colors. The color is determined by the material used in the diode. As electrons move from the N-type material to the P-type material, electrons drop to a lower orbit and release energy. The distance the electrons have to drop depends on the material and determines the color of lights.

Class Assignment: Control an LED display with the Arduino chip

Insert the LED number display so that it spans the central divider of the breadboard. If the display does not fit snugly on the breadboard, check to see that all pins are straight and press firmly.

Wire one cathode (referred to as a common cathode on the diagram) to the negative power track (ground).

Specifications
Single Digit LED Display (276-0075) Specifications Faxback Doc. # 38029 Type: .............................................................. S321R Pinout: Pin 1: .......................................................... Anode F Pin 2: .......................................................... Anode G Pin 3: .............................................................. N/C Pin 4: ................................................... Common Cathode Pin 5: .............................................................. N/C Pin 6: .......................................................... Anode E Pin 7: .......................................................... Anode D Pin 8: .......................................................... Anode C Pin 9: .................................. RHDP (Right Hand Decimal Point) Pin 10: .............................................................. N/C Pin 11: .............................................................. N/C Pin 12: ................................................... Common Cathode Pin 13: .......................................................... Anode B Pin 14: .......................................................... Anode A NOTE: Pins 4 & 12 are internally connected

Specifications

Single Digit LED Display
(276-0075)                 Specifications             Faxback Doc. # 38029

Type: .............................................................. S321R

Pinout:

Pin  1: .......................................................... Anode F
Pin  2: .......................................................... Anode G
Pin  3: .............................................................. N/C
Pin  4: ................................................... Common Cathode
Pin  5: .............................................................. N/C
Pin  6: .......................................................... Anode E
Pin  7: .......................................................... Anode D
Pin  8: .......................................................... Anode C
Pin  9: .................................. RHDP (Right Hand Decimal Point)
Pin 10: .............................................................. N/C
Pin 11: .............................................................. N/C
Pin 12: ................................................... Common Cathode
Pin 13: .......................................................... Anode B
Pin 14: .......................................................... Anode A

NOTE:  Pins 4 & 12 are internally connected

Radio Shack Common Cathode Pins

1          14
2    _     13
   |   |   12
4    _
   |   |
6    _     9
7          8

To light the different LED segments, you will experiment by connecting wires between the the different anode pins to a resistor to power. Keep track of your results.

Write down on a piece of paper which pin lights up which segment.

Don't forget to connect pins 2-9 with 220Ω resistors.
Connect a push button using a 10K pull-down resistor.
Connect two LEDs using 220Ω resistors.

Create a program that when a user presses the push button, a countdown of digits is displayed, and when the number 0 is displayed have the two LEDs blink.

code hints:
Previous Assignment counting Button presses
Create methods to turn on particular numbers:

void led1(){

}

void loop(){
//....
switch (btnPresses) {
    case 0:
      //do something when var == 1
      led1();
      break;
      // break is optional
    case 1:
      //do something when var == 2
      break;
      
    //continue...
    
    default: 
      // if nothing else matches, do the default
      // default is optional
  }

/ / Cascading

Two of these connections simply extend the same clock and latch signal from the Arduino to the second shift register (yellow and green wires). The blue wire is going from the serial out pin (pin 9) of the first shift register to the serial data input (pin 14) of the second register.

Add a second 7-segment LED display

Dual Array

     	//**************************************************************//
//  Name    : shiftOutCode, Predefined Dual Array Style         //
//  Author  : Carlyn Maw, Tom Igoe                              //
//  Date    : 25 Oct, 2006                                      //
//  Version : 1.0                                               //
//  Notes   : Code for using a 74HC595 Shift Register           //
//          : to count from 0 to 255                            //
//****************************************************************

//Pin connected to ST_CP of 74HC595
int latchPin = 8;
//Pin connected to SH_CP of 74HC595
int clockPin = 12;
////Pin connected to DS of 74HC595
int dataPin = 11;

//holders for infromation you're going to pass to shifting function
byte dataRED;
byte dataGREEN;
byte dataArrayRED[10];
byte dataArrayGREEN[10];

void setup() {
  //set pins to output because they are addressed in the main loop
  pinMode(latchPin, OUTPUT);
  Serial.begin(9600);

  //Arduino doesn't seem to have a way to write binary straight into the code 
  //so these values are in HEX.  Decimal would have been fine, too. 
  dataArrayRED[0] = 0xFF; //11111111
  dataArrayRED[1] = 0xFE; //11111110
  dataArrayRED[2] = 0xFC; //11111100
  dataArrayRED[3] = 0xF8; //11111000
  dataArrayRED[4] = 0xF0; //11110000
  dataArrayRED[5] = 0xE0; //11100000
  dataArrayRED[6] = 0xC0; //11000000
  dataArrayRED[7] = 0x80; //10000000
  dataArrayRED[8] = 0x00; //00000000
  dataArrayRED[9] = 0xE0; //11100000

  //Arduino doesn't seem to have a way to write binary straight into the code 
  //so these values are in HEX.  Decimal would have been fine, too. 
  dataArrayGREEN[0] = 0xFF; //11111111
  dataArrayGREEN[1] = 0x7F; //01111111
  dataArrayGREEN[2] = 0x3F; //00111111
  dataArrayGREEN[3] = 0x1F; //00011111
  dataArrayGREEN[4] = 0x0F; //00001111
  dataArrayGREEN[5] = 0x07; //00000111
  dataArrayGREEN[6] = 0x03; //00000011
  dataArrayGREEN[7] = 0x01; //00000001
  dataArrayGREEN[8] = 0x00; //00000000
  dataArrayGREEN[9] = 0x07; //00000111

  //function that blinks all the LEDs
  //gets passed the number of blinks and the pause time
  blinkAll_2Bytes(2,500); 
}

void loop() {


  for (int j = 0; j < 10; j++) {
    //load the light sequence you want from array
    dataRED = dataArrayRED[j];
    dataGREEN = dataArrayGREEN[j];
    //ground latchPin and hold low for as long as you are transmitting
    digitalWrite(latchPin, 0);
    //move 'em out
    shiftOut(dataPin, clockPin, dataGREEN);   
    shiftOut(dataPin, clockPin, dataRED);
    //return the latch pin high to signal chip that it 
    //no longer needs to listen for information
    digitalWrite(latchPin, 1);
    delay(300);
  }
}



// the heart of the program
void shiftOut(int myDataPin, int myClockPin, byte myDataOut) {
  // This shifts 8 bits out MSB first, 
  //on the rising edge of the clock,
  //clock idles low

  //internal function setup
  int i=0;
  int pinState;
  pinMode(myClockPin, OUTPUT);
  pinMode(myDataPin, OUTPUT);

  //clear everything out just in case to
  //prepare shift register for bit shifting
  digitalWrite(myDataPin, 0);
  digitalWrite(myClockPin, 0);

  //for each bit in the byte myDataOut…
  //NOTICE THAT WE ARE COUNTING DOWN in our for loop
  //This means that %00000001 or "1" will go through such
  //that it will be pin Q0 that lights. 
  for (i=7; i>=0; i--)  {
    digitalWrite(myClockPin, 0);

    //if the value passed to myDataOut and a bitmask result 
    // true then... so if we are at i=6 and our value is
    // %11010100 it would the code compares it to %01000000 
    // and proceeds to set pinState to 1.
    if ( myDataOut & (1<<i) ) {
      pinState= 1;
    }
    else {	
      pinState= 0;
    }

    //Sets the pin to HIGH or LOW depending on pinState
    digitalWrite(myDataPin, pinState);
    //register shifts bits on upstroke of clock pin  
    digitalWrite(myClockPin, 1);
    //zero the data pin after shift to prevent bleed through
    digitalWrite(myDataPin, 0);
  }

  //stop shifting
  digitalWrite(myClockPin, 0);
}


//blinks the whole register based on the number of times you want to 
//blink "n" and the pause between them "d"
//starts with a moment of darkness to make sure the first blink
//has its full visual effect.
void blinkAll_2Bytes(int n, int d) {
  digitalWrite(latchPin, 0);
  shiftOut(dataPin, clockPin, 0);
  shiftOut(dataPin, clockPin, 0);
  digitalWrite(latchPin, 1);
  delay(200);
  for (int x = 0; x < n; x++) {
    digitalWrite(latchPin, 0);
    shiftOut(dataPin, clockPin, 255);
    shiftOut(dataPin, clockPin, 255);
    digitalWrite(latchPin, 1);
    delay(d);
    digitalWrite(latchPin, 0);
    shiftOut(dataPin, clockPin, 0);
    shiftOut(dataPin, clockPin, 0);
    digitalWrite(latchPin, 1);
    delay(d);
  }
}

//Pin connected to ST_CP of 74HC595 int latchPin = 8; //Pin connected to SH_CP of 74HC595 int clockPin = 12; ////Pin connected to DS of 74HC595 int dataPin = 11; //holders for infromation you're going to pass to shifting function byte data; byte dataArray[10]; void setup() { //set pins to output because they are addressed in the main loop pinMode(latchPin, OUTPUT); Serial.begin(9600); //Arduino doesn't seem to have a way to write binary straight into the code //so these values are in HEX. Decimal would have been fine, too. dataArray[0] = 0xFB; //11111011 dataArray[1] = 0x60; //01100000 dataArray[2] = 0xDD; //11011101 dataArray[3] = 0xF5; //11110101 dataArray[4] = 0x66; //01100110 dataArray[5] = 0xB7; //10110111 dataArray[6] = 0xBF; //10111111 dataArray[7] = 0xE0; //11100000 dataArray[8] = 0xFF; //11111111 dataArray[9] = 0xE6; //11100110 //function that blinks all the LEDs //gets passed the number of blinks and the pause time blinkAll(2,500); } void loop() { for (int j = 0; j < 10; j++) { //load the light sequence you want from array data = dataArray[j]; //ground latchPin and hold low for as long as you are transmitting digitalWrite(latchPin, 0); //move 'em out shiftOut(dataPin, clockPin, data); //return the latch pin high to signal chip that it //no longer needs to listen for information digitalWrite(latchPin, 1); delay(1000); } } // the heart of the program void shiftOut(int myDataPin, int myClockPin, byte myDataOut) { // This shifts 8 bits out MSB first, //on the rising edge of the clock, //clock idles low //internal function setup int i=0; int pinState; pinMode(myClockPin, OUTPUT); pinMode(myDataPin, OUTPUT); //clear everything out just in case to //prepare shift register for bit shifting digitalWrite(myDataPin, 0); digitalWrite(myClockPin, 0); //for each bit in the byte myDataOut //NOTICE THAT WE ARE COUNTING DOWN in our for loop //This means that %00000001 or "1" will go through such //that it will be pin Q0 that lights. for (i=7; i>=0; i--) { digitalWrite(myClockPin, 0); //if the value passed to myDataOut and a bitmask result // true then... so if we are at i=6 and our value is // %11010100 it would the code compares it to %01000000 // and proceeds to set pinState to 1. if ( myDataOut & (1<<i) ) { pinState= 1; } else { pinState= 0; } //Sets the pin to HIGH or LOW depending on pinState digitalWrite(myDataPin, pinState); //register shifts bits on upstroke of clock pin digitalWrite(myClockPin, 1); //zero the data pin after shift to prevent bleed through digitalWrite(myDataPin, 0); } //stop shifting digitalWrite(myClockPin, 0); } //blinks the whole register based on the number of times you want to //blink "n" and the pause between them "d" //starts with a moment of darkness to make sure the first blink //has its full visual effect. void blinkAll(int n, int d) { digitalWrite(latchPin, 0); shiftOut(dataPin, clockPin, 0); digitalWrite(latchPin, 1); delay(200); for (int x = 0; x < n; x++) { digitalWrite(latchPin, 0); shiftOut(dataPin, clockPin, 255); digitalWrite(latchPin, 1); delay(d); digitalWrite(latchPin, 0); shiftOut(dataPin, clockPin, 0); digitalWrite(latchPin, 1); delay(d); } }

//Pin connected to ST_CP of 74HC595 int latchPin = 8; //Pin connected to SH_CP of 74HC595 int clockPin = 12; ////Pin connected to DS of 74HC595 int dataPin = 11; //holders for infromation you're going to pass to shifting function byte dataHIGH; byte dataLOW; byte dataArrayLow[10]; byte dataArrayHigh[10]; void setup() { //set pins to output because they are addressed in the main loop pinMode(latchPin, OUTPUT); Serial.begin(9600); //Arduino doesn't seem to have a way to write binary straight into the code //so these values are in HEX. Decimal would have been fine, too. dataArrayLow[0] = 0xFB; //11111011 dataArrayLow[1] = 0x60; //01100000 dataArrayLow[2] = 0xDD; //11011101 dataArrayLow[3] = 0xF5; //11110101 dataArrayLow[4] = 0x66; //01100110 dataArrayLow[5] = 0xB7; //10110111 dataArrayLow[6] = 0xBF; //10111111 dataArrayLow[7] = 0xE0; //11100000 dataArrayLow[8] = 0xFF; //11111111 dataArrayLow[9] = 0xE6; //11100110 dataArrayHigh[0] = 0x00; //00000000 dataArrayHigh[1] = 0x60; //01100000 dataArrayHigh[2] = 0xDD; //11011101 dataArrayHigh[3] = 0xF5; //11110101 dataArrayHigh[4] = 0x66; //01100110 dataArrayHigh[5] = 0xB7; //10110111 dataArrayHigh[6] = 0xBF; //10111111 dataArrayHigh[7] = 0xE0; //11100000 dataArrayHigh[8] = 0xFF; //11111111 dataArrayHigh[9] = 0xE6; //11100110 //function that blinks all the LEDs //gets passed the number of blinks and the pause time blinkAll(2,500); } void loop() { for (int i = 0; i < 10; i++) { for (int j = 0; j < 10; j++) { //load the light sequence you want from array dataHIGH = dataArrayHigh[i]; dataLOW = dataArrayLow[j]; //ground latchPin and hold low for as long as you are transmitting digitalWrite(latchPin, 0); //move 'em out shiftOut(dataPin, clockPin, dataHIGH); shiftOut(dataPin, clockPin, dataLOW); //return the latch pin high to signal chip that it //no longer needs to listen for information digitalWrite(latchPin, 1); delay(1000); } } } // the heart of the program void shiftOut(int myDataPin, int myClockPin, byte myDataOut) { // This shifts 8 bits out MSB first, //on the rising edge of the clock, //clock idles low //internal function setup int i=0; int pinState; pinMode(myClockPin, OUTPUT); pinMode(myDataPin, OUTPUT); //clear everything out just in case to //prepare shift register for bit shifting digitalWrite(myDataPin, 0); digitalWrite(myClockPin, 0); //for each bit in the byte myDataOut //NOTICE THAT WE ARE COUNTING DOWN in our for loop //This means that %00000001 or "1" will go through such //that it will be pin Q0 that lights. for (i=7; i>=0; i--) { digitalWrite(myClockPin, 0); //if the value passed to myDataOut and a bitmask result // true then... so if we are at i=6 and our value is // %11010100 it would the code compares it to %01000000 // and proceeds to set pinState to 1. if ( myDataOut & (1<<i) ) { pinState= 1; } else { pinState= 0; } //Sets the pin to HIGH or LOW depending on pinState digitalWrite(myDataPin, pinState); //register shifts bits on upstroke of clock pin digitalWrite(myClockPin, 1); //zero the data pin after shift to prevent bleed through digitalWrite(myDataPin, 0); } //stop shifting digitalWrite(myClockPin, 0); } //blinks the whole register based on the number of times you want to //blink "n" and the pause between them "d" //starts with a moment of darkness to make sure the first blink //has its full visual effect. void blinkAll(int n, int d) { digitalWrite(latchPin, 0); shiftOut(dataPin, clockPin, 0); digitalWrite(latchPin, 1); delay(200); for (int x = 0; x < n; x++) { digitalWrite(latchPin, 0); shiftOut(dataPin, clockPin, 255); digitalWrite(latchPin, 1); delay(d); digitalWrite(latchPin, 0); shiftOut(dataPin, clockPin, 0); digitalWrite(latchPin, 1); delay(d); } }

PINS 1-7, 15	Q0 Q7	Output Pins
PIN 8	GND	Ground, Vss
PIN 9	Q7	Serial Out
PIN 10	MR	Master Reclear, active low
PIN 11	SH_CP	Shift register clock pin
PIN 12	ST_CP	Storage register clock pin (latch pin)
PIN 13	OE	Output enable, active low
PIN 14	DS	Serial data input
PIN 16	Vcc	Positive supply voltage

/ / navigation

/ / Using a seven segment LED Display

Radio Shack Common Cathode Pins

/ / 74HC595 IC

Extend your Arduino with one shift register

/ / Cascading

Dual Array

/ /